Constant ON-time control is widely used in switching converter per fast transient response, simple circuit structure and smooth mode transition. A constant ON-time control circuit for controlling a switching converter usually provides a comparison signal by comparing an output signal of the switching converter with a reference signal, and provides a switching control signal to control the switching converter based on the comparison signal. For example, when the output signal is less than the reference signal, the comparison signal becomes high voltage level and the switching control signal is configured to turn ON the switching converter.
Generally, the constant ON-time control circuit comprises a sequential logic circuit configured to receive the comparison signal and generate the switching control signal. However, the sequential logic circuit introduces metastability. In order to improve stability and insure a fast transient response meanwhile, the constant ON-time control circuit needs to be improved.